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I I I I I I I I I I I I I I I I I I I 1.4 Water Quality Pollution Risks There are many potential pollution sources along the North Fork, including major coal mining operations, gravel mining, cattle and sheep ranches, multiple ,small-town wastewater treatment discharges, as well as intensive irrigation of numerous crops, and ISDSs. Historical water quality sampling results indicate that the water quality in the North Fork area is generally good, although the local geology, land use, and hydrology create changes in water chemistry consistent with the journey of that water from mountain streams to farm fields. The Colorado Water Quality Control Division divides all waterways in the State into numbered segments. Water quality standards are then applied on a segment-by-segment basis. Table 1.3 shows the three stream segments sampled by the North Fork Volunteer Water Quality Monitoring Project and the State's water quality standards for those segments. Has the North Fork Been Meeting Colorado State Standards? Due to intensive use of the North Fork for industry, agriculture, and recreation there is significant interest in maintaining and improving the quality of this resource for all uses. The CDPHE's Water Quality Control Division lists the North Fork of the Gunnison River as a State/Tribal Unified Watershed Assessment high- priority watershed. Although there are currently no segments of the mainstem of the North Fork that qualify for the State's list of most polluted waters, also called the 303(d) list, Leroux Creek did make the 2002 303( d) list for elevated selenium concentrations. Certain other tributaries are on the State's Monitoring and Evaluation List. Placement on this list indicates , that there is the potential for pollution problems, although additional data is needed to make an accurate assessment. _ Tributaries currently on the 2002 Monitoring and Evaluation List include Terror, Hubbard, Minnesota, and Cottonwood Creeks. All were listed for elevated selenium concentrations. Paonia Reservoir Selenium is a metal commonly found in the Mancos shale ( adobe) soils present throughout western Colorado. Selenium may be leached from the soil and into local waterways, when water used for irrigation or other purposes passes through soils derived from the Mancos shale. Selenium then bioaccumulates in aquatic systems, and may eventually cause reproductive problems and deformities in fish and waterfowl. In addition, significant human consumption of fish containing high concentrations of selenium, may also result in toxic human health problems. 1-6